However, the real threat from any edged weapon is not from a cut, but from penetration of the blade into the body. A cut that does not sever an artery or vein will not be immediately deadly. However, a blade that penetrates more than 2 inches into the body may immediately produce lethal results. The famous military tactician and historian Vegetius wrote how the Romans would laugh at their much larger opponents who would slash and hack with the edge of their weapons rather than stab and thrust. The smaller Romans would use straight thrusts with their short swords and defeat their larger opponents with ease.
The more things change, the more they stay the same
Department of Justice statistics on edged weapon assaults indicate that the first 3-5 strikes in an edged weapon attack are slashes and are not lethal. Studies of edged weapon attacks have shown that people are generally repulsed by the thought of shoving an edged weapon into someone. You may slash at a person with the intent of making them stay away from you or to intimidate the person, but a thrust means you intend to hurt or kill the person. Most people, even when in danger, find it difficult to form this deadly intent.